JPH05249488A - Active matrix type liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain the active matrix type liquid crystal display device which enables the removal of the point defects to become bright points without adversely affecting ambient liquid crystals with relatively simple operations. CONSTITUTION:When a picture element of a defective TFT is discovered at the time of production, this picture element electrode 7 is electrically connected to a gate line 2. The connection of the gate line 2 and the picture element electrode 7 is executed by extending the extended part 4a of a gate electrode 4 or the branch part of the gate line 2 to the lower side of the picture element electrode 7 and thermally welding only the overlap part of this picture element electrode 7 and the extended part 4a or the branch part for the picture element having the defect by a laser beam, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device in which a thin film transistor (hereinafter abbreviated as TFT) is provided for each pixel and a switching operation is performed to display an image.

[0002]

2. Description of the Related Art Basically, an active matrix type liquid crystal display device of this type has gate lines and source lines arranged in a matrix on one glass substrate, and TFTs and pixel electrodes are provided at the intersections thereof. An array substrate is provided on which an array substrate is formed, an opposite substrate having a common electrode formed on the other glass substrate is formed, an alignment film is formed on the upper surfaces of the array substrate and the opposite substrate, and the substrates are bonded in parallel with a gap. A liquid crystal is sealed between the counter substrate and the counter substrate.

When a liquid crystal display device is driven, a TFT arranged in each pixel is switched to control a voltage applied between each pixel electrode and a counter electrode. Generally, the TFT is turned off. At this time, each pixel transmits light from the backlight, and when the TFT is on-controlled, screen display is performed so that each pixel blocks light from the backlight.

Therefore, a large number of Ts arranged for each pixel are provided.
If there is a disconnection defect in a very small part of the FT,
Since the defective TFT remains off and passes through the backlight, that portion always appears as a bright spot, resulting in a very conspicuous point defect.

[0005]

Therefore, conventionally, when this kind of point defect appears in the manufacturing stage of a liquid crystal display device, the whole pixel electrode on the array substrate of the point defect portion is irradiated with laser light or the like. It has been proposed to remove the point defect that becomes a bright point and make it a dark point (Japanese Patent Laid-Open No. 2-12761).
No. 4, etc.).

However, in this conventional method, the entire pixel electrode which causes a point defect is thermally melted and removed by irradiation with laser light or the like, and therefore, when the pixel is large or the pixel shape is complicated, The work of removing the entire pixel electrode by light requires a lot of time together with the skill and has a problem that work efficiency is lowered. Further, since the relatively large area of the entire pixel electrode is irradiated with laser light for a long time to thermally melt the pixel electrode, the gas generated in the liquid crystal panel at the time of melting penetrates into the surrounding liquid crystal and the liquid crystal molecules are aligned. There is a problem that it worsens or causes spots on the display screen.

The present invention has been made in view of the above points, and it is an object of the present invention to remove a point defect which becomes a bright spot by a relatively simple operation without adversely affecting the surrounding liquid crystal. It is an object of the present invention to provide an active matrix type liquid crystal display device which can be manufactured.

[0008]

In the active matrix type liquid crystal display device of the first invention of the present invention, a large number of pixel electrodes are arranged in a portion surrounded by each gate line and each source line arranged in a matrix. An active matrix type in which liquid crystal is sealed between an array substrate having a large number of thin film transistors arranged at each intersection of each gate line and each source line and a counter electrode having a common electrode. A liquid crystal display device is characterized in that a pixel electrode of a defective pixel portion is electrically connected to the gate line.

Further, in the active matrix type liquid crystal display device of the second invention, a large number of pixel electrodes are arranged in a portion surrounded by each gate line and each source line arranged in a matrix and each gate line is formed. In an active matrix type liquid crystal display device in which liquid crystal is enclosed between an array substrate having a large number of thin film transistors arranged at each intersection of a line and each source line, and a counter electrode having a common electrode, each gate A power supply line for a defect is arranged along the line or the source line, and the power supply line for the defect is connected to a pixel electrode of a pixel portion having a defect.

[0010]

In the active matrix type liquid crystal display device of the first invention, the scanning signal voltage is applied to the gate line at the time of driving, but the pixel electrode of the TFT which remains off due to a disconnection defect or the like is also connected to the gate line from the gate line. A voltage is applied, the liquid crystal of the pixel is driven by the potential difference between the pixel electrode and the counter electrode, the pixel which should be a bright spot due to the defect is displayed as a dark spot, and the bright spot as the defect does not appear.

Further, the connection between the gate line and the pixel electrode at the time of manufacturing is such that the extension of the gate line is extended to the bottom of the pixel electrode, and for a defective pixel, only the overlapping portion between the pixel electrode and the extension is Since it suffices to heat-melt and connect with a laser beam or the like, the work can be performed relatively easily, and the surrounding liquid crystal is hardly adversely affected.

In the active matrix type liquid crystal display device of the second invention, at the time of driving, a predetermined voltage is applied to the defect power supply line arranged along each gate line or source line. Therefore, the pixel electrode of the defective TFT is
A voltage is applied through the defect power supply line, the liquid crystal of that pixel is driven by the potential difference between the pixel electrode and the counter electrode, and the pixel that should be the bright spot due to the defect is displayed as a dark spot, and the bright spot as the defect is displayed. No dots appear.

The connection between the defective power supply line and the pixel electrode at the time of manufacturing is performed by extending the extended part of the defective power supply line to the position below the pixel electrode, and for a defective pixel, the pixel electrode and the extended part overlap each other. Since only a part needs to be heat-melted and connected by a laser beam or the like, the work can be performed relatively easily and the surrounding liquid crystal is hardly adversely affected.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show an embodiment of the first invention, and FIG. 1 shows a schematic plan view of an array substrate 10 in an active matrix type liquid crystal display device. Reference numeral 1 is a source line, and 2 is a gate line, which are arranged in a matrix on the glass substrate 8. The source line 1 is formed of a metal such as aluminum and the gate line 2 is formed of a metal such as chromium by a sputtering method, a photolithography method, or the like, and an insulating layer 13 such as a-Si is formed at the intersection of the source line 1 and the gate line 2. Is inserted.

TFTs 6 are arranged at the intersections of the source lines 1 and the gate lines 2, respectively.
The pixel electrode 7 is formed of ITO or the like in each region surrounded by the gate line 2.

The TFT 6, as shown in the sectional view of FIG.
The gate electrode 4 is formed on the glass substrate 8 by connecting it to the gate line 2 by a metal such as chromium, the insulating film 12 such as silicon nitride is formed on the gate electrode 4, and the active layer 9 is formed on the insulating film 12 by a. -Si or the like, on which n-type a is formed
A doping layer 14 such as -Si is formed. Then, the source electrode 3 and the drain electrode 5 are formed on the doping layer 14.
Are formed of aluminum or the like, the source electrode 3 is connected to the source line 1, and the drain electrode 5 is connected to the pixel electrode 7.

Further, an extension portion 4a is provided on the gate electrode 4 of the TFT 6, and the extension portion 4a enters under the pixel electrode 7 as shown in FIG. 3 and is located between the extension portion 4a and the pixel electrode 7. The insulating film 12 is inserted.

On the surface of the array substrate 10 thus formed, a protective film 11 made of silicon nitride or the like is formed on the portion except the pixel electrode 7, and an alignment film 16 made of polyimide or the like is further formed. An opposite substrate (not shown) arranged so as to face the array substrate 10 is I on another glass substrate.
A common electrode made of TO or the like is formed, and an alignment film is formed on the surface of the common electrode.

Then, after rubbing the surfaces (the alignment film side) of the array substrate 10 and the counter substrate, the array substrate 1
0 and the counter substrate are bonded in parallel with a slight gap,
Liquid crystal is enclosed between them to form a liquid crystal panel.

After that, a drive circuit is connected to each source line 1 and gate line 2 of the liquid crystal panel, an AC drive signal is supplied to each source line 1, and a scanning signal is supplied to the gate line 2 to inspect the liquid crystal panel. I do.

When the TFT has a disconnection defect or the like, the TFT remains off even during driving, and the liquid crystal of the pixel is not driven. If such a defective TFT is found during inspection, laser light is irradiated to the pixel electrode 7 and its extension portion 4a of the pixel having the defective TFT by irradiating the pixel electrode 7 and the pixel electrode 7 with the laser light. A part of the lower insulating film 12 is thermally melted.

As a result, in the pixel having the defective TFT, a part of the pixel electrode 7 abuts on the extension 4a therebelow,
The pixel electrode 7 and the gate electrode 4 are electrically connected. Since the work at this time may be performed by irradiating the laser light only on the overlapping portion of the pixel electrode 7 and the extension 4a to melt it, the work is relatively easy as compared with the conventional work of removing the entire pixel electrode. It can be performed, and the gas generation is small, and the adverse effect on the surrounding liquid crystal is small.

The liquid crystal display device manufactured in this manner supplies an AC drive signal to the source line 1 and the gate line 2
The gate line 2 is driven by supplying a scanning signal to the gate electrode 4 and the defect T through the gate electrode 4 and its extension 4a.
It is also applied to the pixel electrode 7 of the pixel having the FT, the liquid crystal of the pixel is driven by the potential difference between the pixel electrode 7 and the counter electrode, and the pixel that should be a bright spot due to the defect is displayed as a dark dot, and as a defect. Does not appear.

For the pixel having the defective TFT, the gate line 2 and the pixel electrode 7 may be connected as described above. Therefore, as shown in FIG. 5, a branch portion 2a is provided in a part of the gate line 2. , The branch portion 2a similar to the extension portion 4a
Can be extended to the lower side of the pixel electrode 7, and the overlapping portion can be connected by laser light.

6 and 7 show an embodiment of the second invention. In the array substrate of FIG. 6, the source line 1 and the gate line 2 are arranged in a matrix, and TFTs are provided at the intersections thereof.
6 is basically the same in structure as that described above, but a defective power supply line (for example, chrome) 14 for supplying power to the pixel electrode 7 of the defective TFT is arranged along the gate line 1. Is set up.

In addition, a branch portion 14 is provided at a part of the defect power supply line 14.
a is provided, the branch portion 14a extends to the lower side of the pixel electrode 7, and the tip thereof is located below the pixel electrode 7 with the insulating layer interposed therebetween. In addition, the defect feed line 14 and the source line 1
An insulating layer 13 made of a-Si or the like is inserted at the crossing position of 1 and the crossing position of the branch line 14a and the gate line 2.

Also in the liquid crystal panel using this array substrate, if a defective TFT such as a disconnection is found during the driving inspection at the time of manufacturing the same as the above, the defect T
In the pixel having FT, the overlapping portion of the pixel electrode 7 and the branch portion 14a is irradiated with laser light to heat-melt the pixel electrode 7 and a part of the insulating film 12 thereunder. As a result, a part of the pixel electrode 7 comes into contact with the branch portion 14a below the pixel electrode 7, and the pixel electrode 7 and the defect power supply line 14 are electrically connected.

Also in this work, as in the above, it is sufficient to irradiate the laser light only on the overlapping portion of the pixel electrode 7 and the branch 14a to melt it, and therefore, compared with the conventional work of removing the entire pixel electrode. The work can be performed relatively easily, the gas generation is small, and the adverse effect on the surrounding liquid crystal is small.

Such a liquid crystal display device is driven by supplying an AC drive signal to the source line 1 and a scanning signal to the gate line 2 and applying a predetermined voltage to the defect power supply line 14. Therefore, a voltage is applied from the defect power supply line 14 to the pixel electrode 7 of the pixel having the defective TFT through the branch portion 14a, the liquid crystal of the pixel is driven by the potential difference between the pixel electrode 7 and the counter electrode, and the defect is caused. Pixels that should be bright spots are displayed as dark spots, and bright spots as defects do not appear.

In the above example, the defect power supply line 14 is arranged along the gate line 2, but the defect power supply line 15 may be arranged along the source line 1 as shown in FIG. .. In this case, the branch portion 1 extending from the defect power supply line 15
5a jumps the source line 1 and enters the lower side of the pixel electrode 7, and the tip of the pixel having a defective TFT is connected to the pixel electrode 7.

[Brief description of drawings]

FIG. 1 is a partial plan view of an array substrate showing an embodiment of the first invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

3 is an enlarged sectional view taken along the line III-III in FIG.

FIG. 4 is an enlarged cross-sectional view showing a state where a pixel electrode 7 and an extension 4a are connected.

FIG. 5 is a partial plan view of another embodiment.

FIG. 6 is a partial plan view of an array substrate showing an embodiment of the second invention.

FIG. 7 is a partial plan view of another embodiment.

[Explanation of symbols]

1-source line, 2-gate line, 4a-extension,
6-TFT, 7-pixel electrode, 10-array substrate, 14-
Defect feeder, 14-branch.

Claims (2)

[Claims] 1. A large number of pixel electrodes are arranged in a portion surrounded by each gate line and each source line arranged in a matrix, and a large number of pixel electrodes are arranged at each intersecting position of each gate line and each source line. In an active matrix type liquid crystal display device in which a liquid crystal is sealed between an array substrate having thin film transistors and a counter electrode having a common electrode, the pixel electrode of a defective pixel portion is the gate line. An active matrix type liquid crystal display device characterized by being electrically connected. 2. A large number of pixel electrodes are arranged in a portion surrounded by each gate line and each source line arranged in a matrix, and a large number of pixel electrodes are arranged at each crossing position of each gate line and each source line. In an active matrix type liquid crystal display device in which liquid crystal is sealed between an array substrate on which the thin film transistors are arranged and a counter electrode on which a common electrode is formed, defect supply along each of the gate lines or the source lines. An active matrix type liquid crystal display device characterized in that an electric wire is provided and the power supply line for the defect is connected to a pixel electrode of a pixel portion having a defect.